Laptop shuts down before windows can open

My daughters laptop shuts down before windows can begin. She wanted to just delete the XP she has on there and put an old disc with windows 98 on it, but it will not stay on long enough to even do that, and when I went to F8 and F12 It will not accept the command choices. You guys out there helped me before, can I call on you one more time? Please!!!

Cheryl